Current available heat pump requires different types of compressors for different range of working environment temperature; therefore, the user may need to install multiple air-conditioning systems such as a combination of a heat pump and a gas heater for different range of working temperature. One of the reasons is the low efficiency of the heat pump under low working temperature; another reason is the need for interrupting operation due to the frost conditions on evaporators.
The current defrosting methods such as electrical defrost system and reverse-circulation defrost system require the heat pump to stop operation while defrosting. Therefore, it is one objective of the present invention to provide an air-condition heat pump capable of uninterrupted operation during system defrosting process.
Another objective of the present invention is to provide the most efficient control methods for cross defrosting heat pump system under different temperature and humidity conditions; most heat pumps require the heat energy from other source to maintain the heating efficiency while the present invention defrosts with the heat energy absorbed from the environment and the heat energy generated by the compressor.
Current compressors have very low efficiency under low temperature range, the current two-stage compressors utilize two compression strokes to increase system efficiency, however, the current two-stage compressors can not operate under different temperature range, in other words, the two-stage compressor can not operate under the environment that does not require pressure boosting; therefore it is another objective of the present invention to provide a multi-stage pressure boosting heat pump system capable of adjusting the level of pressure boosting in order to operate under a wide range of working environment temperature.
Current ventilation and humidity control systems can not fully utilize the heat energy in the indoor air exhaust; therefore it is yet another objective to provide a ventilation and humidity control system to combine with the multi-range cross defrosting heat pump systems of the present invention. The ventilation and humidity control system recycles the heat energy from the indoor exhaust and adjusts the ventilation rate according to the humidity percentage. For the human comfort in most indoor space, the ventilation rate required is directly proportional to the humidity percentage, the ventilation and humidity control system of the present invention raises the ventilation rate by automatically adjusting the defrosting duration, since the multi-range cross defrosting heat pump system of the present invention requires more defrosting time when the humidity percentage of the working environment is high.
In general, current heat pump system has very limited range of working temperatures due to the limitation and the operation efficiency of the compressor; however, in many circumstances, the environment temperature may vary from negative 40 degree to 20 degree Celsius, therefore it is main objective of the present invention to provide a multi-range cross defrosting heat pump capable of operating under a wide range of working environment temperature at high efficiency.